Below is a list of potential causes of water ingress in the mk7 / mk7.5 Golf, which under the skin is very similar to the mk3 / mk3.5 Leon so it could be worth using it as a basis for trying to locate the source of your water ingress
problem. I don’t own a Leon so I don’t know if all of the items below would be relevant to your car;
- Blocked / waterlogged pollen filter.
- Cars with sunroof; blocked sunroof drain tubes.
- Leaking door speaker seals (in the Golf, it’s the rear door speaker seals that are prone to failing).
- A/C drain tube draining into car interior.
- Deformed or damaged door / window seals.
The above items are likely to result in damp carpets and carpet mats so check for dampness.
- Tailgate handle drain tube becoming detached from the rubber grommet at the bottom edge of the tailgate. I don’t know if the Leon has the same / similar type of drainage tube - quick way to check is to open the tailgate to see if there’s a rubber grommet in the centre of the bottom edge immediately below the tailgate release handle. The rubber grommet at the exit point of the tube can perish over time leaving the tube loose to drain into the inside of the tailgate. If this happens, water collecting inside the tailgate drains into the luggage compartment.
- Damaged / perished rear light cluster seals.
- Poor seal around the air pressure equalisation vents / flaps behind the rear bumper.
If any of the above three are the cause of a leak, tale signs are likely to be water on the boot floor and / or in the spare wheel well.
- Poor seal between tailgate hinges and hinge mounting points above tailgate / hatch opening.
- Damaged / perished seal between roof mounted aerial and roof panel - check roof lining for water staining.
- Entry and exit points of the wiring loom from the car into the tailgate above the hatch opening. The rubber sleeving protecting the wiring can become damaged or may have worked loose at the attachment points of the sleeving to the bodywork and tailgate. Check the roof lining above at the back of the car above the luggage compartment for water staining.
The above three potential water ingress causes will normally result in staining to the roof lining, a damp rear seat or water in the boot / spare wheel well.
